Petrology and Structural Characterization of Post-Neoproterozoic Dolerites from the Kimberlite Fields in the Kéniéba Region (Western Mali)

Post-Neoproterozoic dolerites from the Kéniéba region (Western Mali) are often associated with kimberlites. The rarity of kimberlite outcrops led to the study of doleritic rocks, spatially associated with them. The petrographic and lithogeochemical study showed that the dolerites of the Kéniéba kimberlitic fields are of tholeiitic nature and of the E-MORB (Enriched-Mid Ocean Ridge Basalt) type. This reflects an enrichment over time, compared to the Birimian dolerites of the volcano-sedimentary greenstone belt of Toumodi, in central C?te d’Ivoire. Furthermore, these dolerites are enriched in SiO2, TiO2, Zr and poor in Fe2O3, MgO. These dolerites would have formed in a late to post-orogenic intracontinental context during the breakup of Gondwana. Structurally, Kéniéba dolerites are often associated with kimberlite pipes, fractures and large deep structures identified using aeromagnetic images. Taking into account the fact that kimberlites do not outcrop in the Kéniéba region, the geochemical study coupled with the interpretation of aeromagnetic data proved to be very useful for the search for pipes.

Predictive Study of Trace Metal Pollution of Gold Panning Sites in Birimian Formations: Case of the Yaouré Furrow (Côte d’Ivoire)

The present study was carried out on small-scale gold mining sites in the Yaouré region of Côte d’Ivoire. This region is geologically representative of the Birimian formations (2.1 Ga) of West Africa. The aim is to determine the potentially toxic trace metals (TMEs) generated by these sites, with a view to preventing possible contamination and/or metal pollution of the waters that provide fish products for local populations. To this end, a sampling campaign was carried out, resulting in the collection of 20 mining waste samples analyzed by X-ray fluorescence spectrometry (XRF) and 10 by X-ray diffractometer (XRD). The XRF analysis detected 06 predominant TMEs: arsenic, chromium, copper, nickel, zinc and vanadium. Statistical analysis was carried out to determine the distributions and correlations between these ETMs. To assess contamination and/or pollution levels, the following indices were calculated on the basis of reference concentrations of upper continental crust MTEs: Enrichment Factor, Geo-accumulation Index, Concentration Factor, Degree of contamination and those related to ecological risks. The results of statistical analyses and indices have shown that arsenic and chromium are the most predominant and can be, depending on the chemical form, potentially more toxic. The results of the DRX analysis show the occurrence of several minerals carrying these two MTEs, especially that of a rare mineral, Stenhuggarite, an arsenic oxide linked to hydrothermal veins. The majority of gold mining operations in West Africa are located in the birimian zone, hence the need for environmental monitoring by the relevant authorities, to prevent potential ecological risks to water and possibly health risks via the food chain.

Experimental Study of a Solar Thermal Incubator Using a Phase-Change Material for Off-Grid Use

The aim of this study was to provide a simple, easy-to-use incubation system for small-scale rural poultry farmers far from the electricity grid. To this end, a naturally ventilated solar thermal incubator was built and experimentally tested. A U-shaped evacuated tube collector and a wooden crate holding 50 eggs were used to build the solar thermal incubator. Water was used as the heat transfer fluid, and an EPCM was integrated into the incubation chamber for operation at night or when the sun was hidden. The heat generated by the solar collector and stored in the heat transfer fluid is transported to the incubation chamber by thermosiphon to heat the chamber. Temperature and humidity probes powered by a solar panel were placed at various locations to monitor the thermo-hygrometric efficiency of the incubation system. The incubator, heated by natural convection, proved to function normally, and the incubation chamber was maintained throughout the incubation period within a temperature range of 35.53˚C to 39.53˚C and relative humidity averaging 49.4% to 68.5%. The experiment was carried out by introducing 30 eggs and the results of the experimental study showed that the incubator’s efficiency was 87%. The performance tests gave a fertility rate of 93% and a hatching rate of 93%, i.e. 28 fertile eggs and 26 hatched eggs, respectively.

Study of the Evolution of Properties of Concrete Containing Used Tire Aggregates

Concrete is generally composed of cement, water, gravel, and sand. However, some research focuses on substituting aggregates with waste materials. In this study, used tires are used as a substitute for gravel. Characteristics such as tensile strength, compressive strength, and porosity were monitored at 7, 14, and 28 days of maturation. The results show that aggregates made from used tires are suitable for concrete production and can replace natural gravel. Regarding the formed concrete, low substitution rates lead to improved concrete properties, but only at an early age. A reaction between the cement and rubber could be the underlying cause. Additionally, the products of this reaction may mitigate the evolution of the compressive strength of the concrete over time.